There is a certain device for gravitational method of processing, “The WEMCO REMER JIG” (Machine Design <<The WEMKO REMER JIG>> WEMCO EQUIPMENT, COAL PLANTS 315C Street, St. Albans, West). It consists of an unmovable trough with sieve and a movable tub with water both are being connected by rubber diaphragm along perimeter. This tub with water is being given vertical reciprocating movement by means of special doubled eccentric mechanism. As a result vertical pulsation of under-sieve water is being achieved that is very important for jigging.
The disadvantages of the machine are the complexity of the design due to the eccentric unit construction, high inertia of the lower part of the machine, that results in high energy-consumption because of the fact that each cycle of jigging needs tub up going with the whole capacity of water as well as low efficiency of mineral processed as there is no simultaneous uprising of the whole bed characteristic of all jiggers with unmovable trough.
There is a device with gravitational processing, a prototype of a jigger for undermining where simultaneously both jigging sieve and working medium (water) pulsate (Chalenko A.—New tendencies in designing jiggers with mobile sieve: Moscow, TSNEETEItyazhmash, 1991, (Mining Equipment, series 2, No. 3, 12).
The machine consists of a unit for loading of material to be processed, a units for unloading material processed, a unit for delivering working medium, a box with a jigging sieve and a tub with the working medium, connected between each other by flexible elastic elements (flat springs) and a drive. The tub has a support shaped as a frame with the shock-absorbers. The machine is a double-mass oscillating system with elastic connection between the masses because of which the jigging sieve and working medium oscillate in counter-phase and it provides their simultaneous pulsation. Along with vertical pulsation of the under-sieve water and vertical pulsation of the jigging sieve simultaneous uprising of the whole bed is being achieved that is very important for jigging process (Bert R. Technology of gravitational processing: Translation from English/Moscow, Nedra, 1990.-219, 220).
Disadvantage for the device is instability of oscillation regime of the working unit and working medium—amplitude of oscillating jigging sieves and water—that influences negatively effectiveness of jigging process, namely decreasing the quality of products dressed as well as there are certain limits in frequency and amplitude of oscillations that decreases the possibility of the further intensification of jigging process for ores with high specific gravity. This is the consequence of the fact that the oscillations of jigging sieve and working medium are being fixed relatively to the center of gravity of a jigger.
As this machine is a double-mass one with elastic connection between masses (by means of flat spring), according to the theory of oscillation of mechanical systems (Vibration in technique. Moscow: machine building, 1978, v.4, part 2, ch.6, p.140, FIG. 5) its work will be characterized by instability of oscillating regime that results in instability of jigging process and as a consequence decreasing of the quality of products dressed. Increasing of amplitude and frequency of oscillation results in greater instability of oscillation regime.